Bill detector



FIG. 1 is a top plan view of a bill detector, showing my new design;

FIG. 2 is a side elevational view thereof;

FIG. 3 is an end elevational view thereof, the opposite end being the same;

FIG. 4 is a side elevational view showing the side opposite of that seen in FIG. 2, and

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a bill detector, substantially as shown and described. 